when you take a strip of paper dip it in heroin and put it on your tongue, let it dissolve, then you lean your head back and let it drip down your throat

A jack off buddy (from 'cum' /'come', meaning 'semen', and 'companion'); a friend that you get together with for sessions of solo or mutual masturbation
Variant of: cumpanion (from 'companion' & 'cum'); jack off buddy & wank bud & JO buddy
Similar to: fuck buddy

doing heroin off of blotter paper